1. Field of the Invention
The present invention relates to the field of turbine generator insulation systems. More specifically, it relates to an improved electrical insulator for stator coil headers and connections and a method for so insulating.
2. Description of the Prior Art
Turbine generators generally produce electric power by rotating a magnet inside coils of copper wires. The rotation of the magnet produces an electrical current within the copper stator coils. The stator has a multitude of slots spaced around its circumference, often having in the neighborhood of 50 such slots. Each slot typically holds a pair of stator coils. Such stator coils are generally comprised of a multitude of copper wires typically interspersed with special water cooling wires that are constructed to allow liquid to flow within them, thereby to cool the stator coil. (Other stator coils utilize hollow tubes and gas cooling.) Even these water cooling wires are conductive.
At the ends of the stator, each coil is connected to another coil in an adjacent slot such that the set of coils is connected in series. In addition, each coil has a header that connects to a main water manifold. The connecting piping is typically made of a non-conductive material such as Teflon.TM..
While the piping from the headers to the water manifold is generally non-conductive, the headers themselves are conductive. Thus, problems of electrical shorting between adjacent unconnected headers can arise. Such shorting could occur if a small piece of metal or other conductive material falls between the two headers, thereby bridging the gap and allowing conduction. To avoid this problem, present methods of insulation consist of applying silicone rubber paste around the header, fitting a cured silicone rubber cover over the header, and then taping over the cover and series connection with a glass tape. Finally, an epoxy resin is brushed on and allowed to cure. Insulating such connections on large turbine generators using these methods can take from seven to nine days.
In addition to the series connections, banks of stator coils are connected with other banks in phase connections. At the present time, the phase coil ends and connections are hand taped with multiple layers of tape, typically made of mica, and then brushed with resin.
In addition to the time consuming nature of the initial insulation process, should maintenance be required on the stator coils or headers, removal of the installed insulation can be just as time consuming. Once maintenance is completed, reinsulation must be performed, involving further extensive labor.
Accordingly, there exists a need for a method and product for electrically insulating stator coil connections and headers economically and efficiently while allowing for economical and efficient maintenance procedures.